The proposed research is concerned with cellular mechanisms of generation and control of focal epileptogenic discharge in the brain. Using techniques for intracellular recording and stimulation, the effects of corticofugal epileptogenic discharge from acute and chronic cortical epileptiform foci upon neuronal activities in contralateral homotopic cortical areas and thalamic relay nuclei (e.g., n. ventralis lateralis) will be investigated as will the neuronal activities in such foci. Experiments will be planned to further explore the phenomenon of antidromic burst generation previously demonstrated in thalamocortical relay cells whose axons project to the area of an acute epileptiform focus.